Civil aviation in Mongolia is not well developed, but it is adequate for the small and sort of poor population. There is one international airport in Ulaan Baatar, and the bigger towns have regional airports. Ulaan Baatar's Chinggis Khaan International Airport is only 18 kilometers away from the capital, so travel there is easy. The call letters are ULN. It is a small airport that was opened in 1961. In 1986, the terminal was upgraded. It is the home base for three Mongolian carriers: MIAT Mongolian Airlines, Eznis Airways, and Aero Mongolia. There are some international flights.
Planes fly from Berlin, London and Moscow. But the flights are irregular, so check the schedules. There are almost daily flights from Seoul on Korean Air. You can also fly in from Tokyo or Beijing. Once you are in the country, you can also fly to all the provincial capitals. See China Highlights' tours to Mongolia
Instead of flying in, another way to get to Mongolia is by train. The Trans-Siberian Railway links Ulaan Baatar with Moscow and Beijing and points in between. From June to October, there are trains going to Ulaan Baatar from Beijing twice a week: K23 and K24 are the scheduled trains. SeeBeijing to Ulan Bator train schedule
Second class (hard sleeper) costs about 200 USD from Beijing to Ulaanbaatar. The train ride takes 30 hours. The tickets are only available at the China International Tour Service (CITS) office on the second floor of the Beijing International Hotel that is about a ten minute walk north of the station. See how to buy train tickets in China?
There is a small hot water maker at the end of each train car that dispenses free hot water. You can use the hot water to drink or make noodles or tea. So bring a container and your favorite noodles.
There are buses to and from Ulaan Baatar and the provincial capitals. But you might not find a bus between other towns and cities. People often just hire a jeep to travel around because there are few paved roads except those that lead to Ulaan Baatar.
For safety's sake, do not carry large amount of cash and valuables with you when you travel. Also, go with partners. Do some research if possible about the drivers of jeeps.
In Ulaan Baatar, taxis cost about 0.50 USD per kilometer. When you get in, make sure that the trip meter is set to zero and that the driver turns it on when he starts to drive. If you get into a vehicle without a meter, negotiate beforehand about the price per kilometer or the cost of the trip.